Patent GB-1405018-A (GB)
Title: Measuring fuel comsumption
IPC: G01F9/00
Filed: 1972-10-19
Abstract: 1405018 Measuring fuel consumption I T T INDUSTRIES Inc 19 Oct 1972 [20 Oct 1971] 48139/72 Heading G1N Apparatus and methods for measuring the fuel consumption of an engine accelerating under constant load, comprises means for detecting the occurrence of each of a plurality of predetermined r.p.m. conditions, second means for sequentially registering and storing a measurement of the fuel per unit time being consumed at each of the plurality of conditions and means coupled to the first and second means to cause the measurement to be taken at each r.p.m. condition sequentially reached by the engine. A pulse train from a tachometer, the frequency of the train being proportional to the r.p.m., is applied to an input gate 1 and passed through a frequency divider 2 to a counter 3, 4, which is controlled by oscillator 10 to count the consecutive time intervals of e.g. 0À2 sec and be reset to zero at the end of each interval and when it attains a certain counted value e.g. 50 in any one interval enables AND gate 5 to trigger a monostable 6 to open AND gate 7 for a certain duration to allow pulses having a frequency indicative of the fuel consumption rate and derived from a flowmeter, not shown, to pass to and be counted at 8. At the start of the measurement a counter 11, which is used to define the divisor of divider 2, is set at "1" and the output of counter 11 is additionally taken to a decoder 12 where a first of 5 output lines 32 is activated which makes ready a NOR gate 13 which is enabled by the Q output of the monostable 6 when this circuit is activated so that the count at 8 is transferred to the first of 5 storage registers. The trailing edge of the monostable pulse causes the counter 11 to be incremented by one, and the monostable pulse is also applied to disable the input gate 1 for its duration. Thus if e.g. 500 r.p.m. is the speed at which the first measurement is required, with the divisor at 2 set at "1", the fuel rate measurement is activated when the pulse is emitted from AND gate 5 indicative that this speed is reached. The counter 11 is then moved to "2" and the next measurement will be made when the speed is 100 r.p.m. and so on. At each measurement the decoder 12 activates a different one of lines 32 so that each result is stored in a different store. The system is stopped by disabling of the gate 1 by a signal on line "6" of decoder 12. In a modification, Fig. 4 (not shown) a free running multi-vibrator (46) is used as a time base and pulses from the flow-rate meter are counted at (48) at each consecutive time base interval and the counter is reset to zero at each interval end. The output from the counter (43), (44) counting r.p.m. pulses and also controlled in the same way by the time base (46) is adapted to set a flip-flop to enable the count being assembled at (8) to be sent to a corresponding store as described above when the correct r.p.m. is detected. The flip-flop is reset by the end of the current time base interval. In a further modification Fig. 5 (not shown) a D.C. tachometer is used and various transistors are selectively enabled by a counter output corresponding to that from decoder 12 above for the sensing of the different speeds to allow the D.C. output to be transmitted to a corresponding threshold device.